Apparatus and process for preventing contamination of centrifugallypurified liquids



Aug. 6, 1929. w R CHADBURN 1,723,329

APPARATUS AND PROCESS FOR PREVENTING CONTAMINATION OF CENTRIFUGALLY PURIFIED LIQUIDS Flled Jan 7 1926 2 Sheets-Sheet 1 F/aj.

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Aug. 6, 1929. w R CHADBURN 1,723,329

' APPARATUS AND PROCESS FOR PREVENTING CONTAMINATION OF CENTRIFUGALLY PURIFIED LIQUIDS 2 Sheets-Sheet 2 Filed Jan. '7, 1926 00 54 77,? MW/m 5 05 Cfiad urn W/r/vass:

Patented Aug. 6, 1929.

UNITED STATES PATENT 1,723,329 OFFICE.

WILLIAM ROY CHADBURN, OF LONDON, ENGLAND, ASEIGNOR TO THE DE LLAVAL SEPARATOR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

APPARATUS AND Pnoonss FOR PREVENTING CONTAMINATION on CENTRIFUGALLY- PURIFIED LIQUIDS.

Application filed January 7, 1926, Serial No. 79,817, and in Great Britain January 27, 1925.

This invention relates to centrifugal liquid puriliers and is mncerned with the degassing and stahilizing of the liquid treated in such nnichines.

Iii-general, centrifugal purifiers are used tor separating solids from a liquid and for separating two liquids mixed together. The purified liquid is ordinarily continuously leaving the centrifugal howl and passes into a statioiniry casing or receiving pan generally placed around the centrifugal howl, from wuich casing it passes out of suitahly disposed spouts into the collecting vessels placed to receive it. In practice, it has'heen found that the liquid tends to become highly aerated.

\Vheu leaving the howl, the liquids are generally very linely divided and pass to the cars ing in the form of a spray. It is evident that during this 1 assage the liquid will he in the host condition to ahsorh or gases. It should turther he noted that when the liquid or liquids leave the using, a greatamount of gas or gases is mechanically mixed into the liquid, and 'l'urcher that the rotating centrifugal howl will cause some pressure in the cars ing. For this latter reason, a great amount o't air leaves the casing or tinware through the outlet spouts. In many cases, this air contains a suhstautial volume of the liquid in a finely divided condition.

In the above descrihed process of purifying liquids .in a cen .i'fuge and discharging them 'inlo an adjacent reciqitacle, where the liquid, in linely divided -lorin, tends to react with air to term an ohjeitiouahlc d'iiXtLUO, it is known to suhszautiall y displace atn'iospheric air in, the receptacle with a neutral gas which does not tend to react chemically with the liquid, so that, concurrently with. the discharge of the liquid from the eentri'luge, the liquid will immediately and while in a finely divided condition penetrate a hody. ol such neutral gas and therehy he protected, while in such linely divided condition, from contact with air and. from such objectionable reaction. improvei'i'ients in this linown process, and comprises means adapted to carry out the known proiiess. It also comprises means to renuwe ohjeiiitionahle gases with which the liquid may have been saturated, completely or portly, when admitted to the centri; "are and their replacement by an inert lilhe present invention compreheuds or desirable gas. It also comprises means adaltited to carry out the improved process.

In the drawings:

Fig. 1 is a view, in side elevation, and some what diagrannnatic, 01 a centri'lfugal apparatus provided with means for carrying out certain of the processes herein described.

Fig. is a similar view of a n'ioditication.

Fig. 3 is a similar view of another modil'i ca ti on.

Fig. is a sectional elevation oil proved collecting vessel.

Fig. 5 is a cross-section of the collecting vessel shown in Fig. l. l

Figure 1 shows the simplest form of the invention, In. this 'ligure the centrifugal bowl 1 is rotating in a :lrame 2. The separator howl is assumed to he one provided with a single outle The liquid leaves the howl in a lincly divided state and collectingin the casing. 3, provided with an outlet spout 4:.

an im- The liquid to he treated is delivered to the centri'liupgil howl through a pipe S, prelcrahly under a slight pressure head, wlnch may he obtained hy means of an elevated tank. 'lhe centrifuge is 'i 'urther connected to a reservoir 7 hy a pipe line 6, the reservoir containing, suitahly under high n'essure, the gas which to he ahsorhml hy the liquid. In the figure the pipe line (3 is connected directly to the casing 3, a preferable hut not necessary arrangen'ient, since the gas to he introduced into the system may he delivered at other positions so long as precautions are taken to insure that the gas supply can pass to the casing 3. The pipe line (5 is provideiil with a valve 8 by which the gas supply can he regulated. This valve is suitahly of such a design that it will automatically keep a suitable over-pressure in the stationary casing. In starting the operation, it is, of course, necessary, or at least desirable, to at first replace the atmospheric air in the system hy the desirable gas.

no I

This is automatically done hy opening the i the stationary casing. I hen leaving the centritugal howl, the liquid is split up into a very great number of small globules. hen passing into the casing 3, the liquid surface in contact with the gas in the casing is very lar e and consequently a great amount of gas will be absorbed by the liquid in a short while. Further, due to the small dimensions of the globules, the absorbed gas will soon penetrate the globules. For the above mentioned reasons, a gas, previously absorbed by the liquid, will rapidly and practically complete ly leave the globules and mix with the desirable gas in the casing As before described, the liquid, when leaving the casing, contains a great amount of gas mechanically mixed into the liquid. This gas is separated in the collecting vessel 9, placed below the outlet spout l. If complete saturation should not have taken place during the passage through the casing 25, the liquid has the capacity of absorbing a further amount of he desirable gas, as the separation in the collecting vessel 9 will often take considerable time. During this time, further replacement of the uncle sirable gas will also take place. The arrange ment a cording to Figure 1 is the simplest one, but has the disadvantage that a considerable quantity of gas must pass through the system and be discharged to the atmosphere after having passed through the centrifuge. The construction described can, however, suitably be used where the desirable gas is of no value, as, for instance, where exhausted gas from gasoline motors can be used,

In cases where a valuable gas, such carbonic acid, oxy en or nitrogen in pure form must be used, the above mentioned system is preferably elaborated by the inclusion of some gas-ecmiomizing arran ements.

Figure 2 shows a suitable term of one such arrangement. The design differs from that shown in Figure 1 in the following respects. The outlet spout at is connected to a collecting vessel provided with a delivery pipe 11. The collecting vessel 10 is suitably provided with means automatically maintaining the liquid level at a suitable heigh 1. According to the drawing, this is effec ed by means of a liquid seal, but, of course, other known regulating means can be used. A vacuum pump 12 is provided for withdrawing theatmosphere in the system when startin Dun ing this air-exhausting period the valve 8 in the pipe line 6 and the valve 13 in the pipe line 11 should be closed. As soon as a vacuum indicator shows a sufliciently low pressure. that is, when the atmosphere air is sufiicieutiy e3;- haustcd, the above mentioned valve 8 is opened. Should one operation of this kin d be insufficient for obtaining an atmosphere sailiciently free from air, the procedure 11 be repcatcd. In this way, an atmosphere practicallji free from air can be obtained. In the drawing. a rotating vacuum pump 12 driven from the centrifuge is shown, but other types of vacuum pumps producing a suifiiciently low Vacuum may be employed for the purpose. If

large quantities of water with sufficiently high pressures are available, a water ejector pump will be found suitable. The pipe line 1 L connecting the vacuum pump with the centrifuge is provided with a valve 15, by which the pum p may be shut oil", when the dc- :ired degree i vacuum has been established. if a repeated air-withdrau'al operation is necssary, the valve 15 preferably cloed in ordnto prevent the desirable gas from being immediately sucked out. The valve to is prcforably made automatically shut the pump from the system as soon as the dili'erence between the atmospheric pressure and the absolute pressure in the system has reached a certain degree. -t will be understood that the beariug immediately below the centrifugal bowl is, of course, spring-support ed in any of die usual ways and that any such spring bearing atlords a surrounding aun ular opening I otwccn the bearing and the frame which permits free communication between the receptacle surrounding the bowl and the enclosure within frame 2 below 5; id bearing. in some -a:; it may be suitable to arrange as follows for obtaining the desired atmosphu'e. The

rho system is completely filed with oil, which is then drawn away from the tem at the lowest point, at the same time allowing the desirable gas to flow into the sys tem. This method can be used when treating, for instance, a lubricating oil.

in order to prevent air from being sucked into the system during the evacuation period and for economizin g with gas during the separation, the frame preferably completely closed. Bushings, from which shafts are protruding, are for this reason provided with packing bones. The drain pipe at the bottom of the bowl frame, which in ordinary parators carries away liquid dripping down from the tinware, must also be closed. When using only a small pressure in excess of atmosphere, this pipe can be dosed by a liquid seal, but when using higher pressure there should be provided other mechanical devices which allow the collected liquid to escape continuously butprevcnt the gas from leaking out to the surrouni'ling atmosphere.

As soon as the desired atmosphere is obtained, thevalvcs and 13 are opener] and liquid is fed into the separator. "lhe separated liquid is then led to the collecti vessel 10, from which it is delive red to another CORP tainer as soon as the level in the vcsse' has reached a certain height. During the time the liquid is lrept in the vessel it), the mechanically enclosed gas apes from the liquid and collects in the vcss l above the liquid level. If the pipe line is piac )d between the casing 3 and the collecting *essel 10, as shown in full lines in the d awing, the collected in the top of the co cting vessel 10 can flow back to the cas ng 23 i-urough the same pipe line used for carrying the liquid from tl'ie ca sing 3 Ill) fill

to the collecting vessel 10. Should such .an

arrangement be impossible, a special pipe line.

16 can be titted for allowing gas to flow from the collecting vessel to the casing 3. This arral'igement is necessary, especially when. the pipe line from the centrifuge is connected to to collection vessel 10 below the liquid level, bymeans of an extension 40 of pipe t.

In the above description, it has been assinned that the casing of the centrifuge is provided with only one compartment. 111 cases where two liquids are to be separately and continuously delivered from the contriituge, two compartments must, of course, be provided, as, for instance, when treating transformer oil containing a great quantity ol. water. Figure 3 shows an arrangement, which suitably can be used for such purposes. The compartment 17 is connected to a collect- .ing vessel 18, which suitably is of the same construction as the vessel 10in Figure 2 and is provided with similar means for regulating the liquid level. In the case where the pipe line and the collecting vessel are connected together above the liquid level in the vessel, the separated out in the vessel can be brought back to the connaartments oi. the easing through the same pipe line. This arrangement is, however, not suitable for all purposes, as it has been found that very strong gas currents between the upper compartment 3 and the bottom compartment 17 can be produced'by such an arrangei'nent. These gas currents attain a great velocity in the space formed between the bowl and the partition between the two compartments of the casing or tinware, andin some instances it has been found that these gas currents can draw oil with them lighter liquid from the compartment 3 down to theheavier liquid in the connpartment 17. In other cases the gas currents may have the opposite direction and will then carry liquid from the latter compartment to the former. In order to prevent this re-mixing of liquids it is desirable to connect the spaces above the liquid level in the collecting vesselsby the pipe line 19. \Vhen separating water from transformer oil, it is absolutely necessary that the oil should be tree from water, and in such cases it is desirable to provide a moisture absorb- :ing arrangement in the pipe line 19. It is also practicable to arrange a water absorber in the pipe line 6 delivering the desirable gas from the gas container 7 to the centrifuge.

If, on the other hand, the pipe lines are connected to the collecting vessels below the liquid surface, special pipe lines, such as 16 in Fig. 2, must be arranged in order to bring the gas, separated in the vessels, back to the con'ipartments 3 and 17 of the tinwarc casing.

In order to economize with the desirable gas, it is advisable to give the collecting vessel such dimensions that the liquid leaving desirable gas mixed with the desirable.

.ihe separated liquid.

the percentage of undesirable gas, awvalve them is free from mechanically enclosed gas. In order to reduce the dimensions of the collecting vessels when using separators of great capacity, an arrangement according to Fig ures i and 5 is desirable. These figures may be assumed to illustrate a collecting vessel which may be substituted for the vessel 10 of Fig. 2 or the vessels 10 and 18 of Fig. The liquid is conducted to a compartment 21 oi the collectin vessel lUt). From the com partment 21 the liquid flows through a number of thin layers formed by partitions 22 in the main part of the vessel. If these partitions form angles with a vertical line, the effect is highly increased. When using collecting vessels without partitions, the gas bubbles, coming into the tank at the bottom, must pass through a. considerable depth oi.

liquid in order to come to the surface. W hen using partitions as shown in Figures 4- and 5, the distance the bubbles have to pass is only the vertical distance between two adjacent partitions. As soon as the bubbles arrive at the lower surface oil the upper tition, they follow the surface upwards to the gas chamber,,and there is no risk of the gas getting mixed with the liquid. Instead of using a rectangular vessel. with straight partitions, cylindrical vessels with conical partitions can be used as well.

The connection of the casing or casings of: the centriilijigc to a collecting vessel or collectiug vessels in order to separate away the gas from the liquid is distinctly pro'lerred, but is .not always necessary. In many cases it sullices to provide the outlet spouts with liquid seals. In such cases a greatamount of mechanically enclosed gases will leave the system together with the liquids. In some cases this may be considered advantageous for the following reasons. As previously pointed out, it is necessary that the atmos phere should be in a sulliciently pure condition and further that during the passage through the casing the liquid can give oll' uriorder to prevent the desirable gas from becoming mixed with undesirable gas to too great an extent, means must be provided, for

carrying the umlesiral'ile gas away from the system. Of course, this can be el'lected by leading away a certain amount of desirable gas from the system, which will. then bring with it a certain amount of undesirable gas. The percentage oi undesirable gas in the atmosphere in the system will be constantas soon as the same amount of undesirable gas has been carried away as is taken up from In order to regulate or valves can be provided, through which a certain amount of the gas is carried away from the system. The eiiiciency of the above described arrangement can be increased by keeping a considerable pressure in excess of Jill) lit) atmospheric pressures in the separating system, as the liquid absorbs more gas at higher pressure than at lower. lVhen the liquid leaves the system, in which certain excess pressure is maintained, it will give off a considerable amount of the absorbed. gas. This gas will then carry away the undesirable gas still remaining in the liquid.

If the use of separating vessels is pr ferred, an absorptiondevice for the undesirable gas should be provided in some part of the system. In this case, the from the separating vessels should be carried away to a container, which may be connected to the pipe line delivering the inert o desirable gas to the system. The container between the separating vessel and the pipe line is, of course, not absolutely necessary. In this pipe line, an absorption device is suitably placed. Should a complete saturation be desired. but found unobtainable in one single operation, it is of course necessary to repeat the treatment, and this can be effected by means of a pinup operating to withdraw the liquid from the separating vessel and deliver it to a tanl: connected to the centrifuge by the pipe line l. After some time this ilr will contain a liquid freed from solid impurities, and at the same time this liquid will be saturated with desirable gas.

The above described arrangements ca 0. so 3e used for treating liquids which have already been treated in one way or another in order to bring adesirable gas into the liquid. By supplying to the casing the same gas that was used for a previous treatment, the gas absorbed by the liquid is not allowed to escape. Should the previous treatment not have given complete saturatiomthe liquid can absorb a further amount of when passing through the casing as before described.

A treatment of the above described kind is suitable for many purposes. lt is, for in stance, possible to replace oxygen, absorbed by lubricating oils, transformer oils, or vegetable oils, by inert gases, such as carbonic acid or nitrogen, in order to prevent changes in the composition of the oils. Further, it is possible to treat boiler feed water in the same way in order to replace the oxygen with. an inert gas and thus prevent corrosion of the boiler.

In the accompanying claims wherein the term neutral gas is used, it is intended to include both inert gases and desirable gasc Having now fully described my invention, what I claim and desire to protect by Letters Patent is: p

1. The combination with a centrifugal purifier and a surrounding casing adapted to receive purified liquid discharged from the purifier, of means including a pipe connection with the purifier to exhaust atmospheric air from the centrifuge and the casing, and means independent of said pipe connection to supply a neutral gas to replace the withdrawn air.

2. The combination with a centrifugal purifier and a surrounding casing adapted to receive purified liquid discharged from the purifier, of a conduit through which the cusing may be supplied with a neutral gas, a col lect-ing vessel, an exit pipe connecting the easing and the collecting vessel, and a gas return pipe, independent of said conduit, connecting the collecting vessel and the casing.

The combination with a centrifugal purifier and a surrounding casing divided into two compartn'ients adapted to receive respectively a heavy liquid and a light liquid discharged from the p uritier, of means to supply both compartments of the casing with a neutral gas, two collecting vessels, closed pipes connecting the respective compartments with the respective vessels, and a pipe for passage of gas connecting the two vessels.

l. The combination with a centrifugal purifier and a surrounding casing adapted to receive mrificd liquid discharged from the purifier, of means to. supply the casing with a neutral gas, a collecting vessel, means to convey both liquid and gas from the casing to the lower part of the collecting vessel, and inclined partitions within the collecting vessel between which the liquid is adapted to flow and along the lower surfaces of which gas bubbles are adapted to escape to above the surface of the liquid in the collecting vessel.

5. In the process of purifying liquids in a centrifuge and discharging them into a separate adjacent receptacle, where the liquid, in finely divided form, tends to react with air to form an objectionable mixture, the process which comprise. displacing air in the receptacle with a neutral gas, centrifugally purifying the liquid and discharging it into the body of neutral gas in the receptacle, conveying the liquid mixed with the neutral gas to a different locus and there separating neutral gas from the liquid, and returning the separated neutral gas to the receptacle along a pathindependent of the paths of flow of the liquid and neutral gas to and from the receptacle.

6. In the process of purifying liquids in a centrifuge and discharging them into a sep arate adjacent receptacle, where the liquid, in finely divided form, tends to react with air to form an objectionable mixture, the process which comprises first exhausting air from the receptacle and centrifuge, then admitting neutral gas to replace the withdrawn air, and centrifugally purifying the liquid and discharging it into the body of neutral gas in the receptacle.

7. In the process of separating liquids of dilferent specific gravity and discharging them into separate compartments, where the liquid, in finely divided form, tends to react with air to form an objectionable mixture, the process which comprises displacing air in the compartments with a neutral centrifugally separating the liquids and discharging them into the respective compartments, conveying the liquids mixed with the neutral gas to two separate loci and there separating neutral gas from the liquid, and establishing a circulation of said neutral gas between. the two loci.

8. In the process of purifying liquids in a centrifuge and discharging them into a separate adjacent receptacle, where the liquid, in. finely divided. -lorin, tends to react with air to form an objectionable mixture, the process which comprises displacing air in the receptacle with a neutral gas, eentriilugally puritying the liquid and discharging it into the body of neutral gas in the receptacle, conveying the purified liquid mixed with the neutral gas to the lower part of a body of such purieied liquid, and arresting the vertical movement 01'? gas bubbles in said body of liquid and guiding said arrested gas bubbles upward in a direction inclined to the vertical to above the surface of said bodyof liquid.

9. In the process of purifying liquids in a centrifuge and discharging them into a separate adjacent receptacle, where the liquid,

in :tinely divided form, tends to react with air to form an objectionable mixture, the process which comprises maintaining an atmosphere of a neutral gas in the receptacle by mixing the liquid to be purified with such neutral gas and then centriiugally purifying the liquid and discharging it into the receptacle along with the neutral gas with which it has been mixed before centritugation.

In testimony of which invention I have hereunto set my hand at London, England, on this 2-1 day of December, 1925.

WILLIAM ROY CI-IADBURN. 

